And harold t



Dec. 11, 1928. 1,695,004

H. BANY ET AL AUTOMAT I C CONTROL SYS TEM Filed July 22, 1927 Inventor-'s: Her-man Bang,

Harold T Seeleg, 5

Their- Abner-neg Patented Dec. 11, 1928.

UNITED STATES PATENT OFFICE.

HERMAN BANY, OF SCOTIA, NEW YORK, AND HAROLD T. SEELEY, OF YEADON, PENN-SYLVANIA, ASSIGNORS TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEXVYORK.

AUTOMATIC CON TROL SYSTEM.

Application filed July 22,

Our invention relates to automatic control systems, and moreparticularly to an improved arrangementfor connecting a generator orother source of currentto a load circuit.

\Vhere a load circuit is adapted to be supplied t'rom several sources,when one of the sources is to be connected thereto it may happen thatthe load circuit is at the time energized from another source, andhassubstantially normal voltage thereon. It may also happen that theload circuit is not supplied from any other source at the time thedesired, sou 0c is to be connected thereto, in which case there is novoltage on the load circuit. In case there is an abnormal load on theload circuit for example in case ofa fault therein, it may happen thatthe load circuit voltage is abnormally low even though another source beconnected thereto. -Whenthe.load circuit is without voltage or isvabnormally low, the source voltage should be adjusted to a rela-- tivelylow value before it is connected to the load circuit, to prevent a largerush of current when the connection is made. WVhenthe load circuit isenergized under normal con-; ditions from some other sonrce,. it isdesirable to make the connection when the sourcevolt-r age is slightlyhigher than the load .circuit voltage, in order to prevent a'fiow ofpower from theload circuit to the sourcewhen the; connection isestablished. I

Where automatic-means are provided foradjustingthe'sourcevoltageinresponse to the relative voltages of the source and the loadcircuit, such means will operate to lower the source voltage when it isvhigher than the voltage ofthe loadcircuitw .Itis desirable in such acase toarrange the apparatus so that the switching means' which connectsthe source to the load circuit shall be closed only when the voltageadplstlng means is opera-t mg to raise the source; voltage from below toabove the voltage of the load circuit,vsince if theswitching means isarranged to close whenever the voltage of the source is slightly.

higher than the voltage of the load circuit it resulting in a reversalof power, since the 1927. Serial No. 207,788.

load circuit will'supply power to the source until the voltage adjustingmeans operates to raise the source voltage.

An object of our invention is to provide a control system of thecharacter described which shall lower the source voltage when it ishigher than the load circuit voltage, and which shall begin to raise thesource voltage again as soon as it has been decreased to a valueslightly below the load circuit voltage, whatever that load circuitvoltage mayhappen to be, when supplied from some other source, and whichshall lower the source voltageto a value at which the switching'meansmay be closed without ail-objectionable rush of current when the loadcircuit is without voltage at the time the source is to be'c'onnectedthereto. r

invention in diagrammatic form. I

Our, invention jwill be better understood from the followingdescription, in connection with the accompanying drawing, audits scopewill be pointed out in the appended claims.

. In the embodiment of'our invention illustrated in the;drawing, we haverepresented 1, suitable means are provided,which we have illustrated ascomprising a motor operated rheostat Sin the circuitof'the shunt fieldwinding-6 of the generator 1. For control' ling the operation of therheostat 5, a control relay 7 is provided which when energized completesa circuit for the motor 8 of the motor operated rheostat and its fieldwinding 9 so that the motor rotates in a direct-ion to increase theresistance in the circuit of the shunt field winding 6, and a controlrelay 10 is provided which when energized completes a circuit for themotor 8 and its field winding 11, whichis wound differentially withrespect to field winding 9, so that the motor 8'.rotates The singlefigure of the drawing shows the.

T ciireuit'voltage the device 13' closes contactsthis voltage in adirection to decrease the resistance in the circuit of the shunt fieldwinding 6.

12 is a,- suita blecontroldeviice which is adapted "to be operatedwhen-it is desired to connect the source 1 to the load circuit 4. Asshown, in the drawing it is a manually controlled switch, but inpractice it may be any other suitable manually or automatically operateddevice, examples of which are wellknown in the art, which is operated atthe proper time to effect the connection-of the source to the loadcircuit. 7

It is desirable that the circuit breaker 3 shall not close aftertheswitch 12 is closed until the voltage of the source 1- has beenincreased from a value slightly below the load circuit voltage in casethe load circuit is energized by some other source to a valueslightlyhigher than the load circuit voltage or the voltage-of-thesource 1-has' been'recluced to a relatively low-value in case the loadcircuitingoi the-switch 12 effects the'completidn of a circuit for thecontrol relay 7to effecta decrease-in the volta e of'tlre source 1 in.case is higher than theload circuit voltage at the time switch 12isclosed.

'13-is-a suitable control device,'e'xampl'es of which are well-known inthe art-{which is voltagesof the source 1 and the load circuit' l; Whenthe source voltage is'less than the load 14 and when the I sourcevoltage is' greater than the load circuit voltage the device 13 closescontacts-15: The contacts 14 are the opens the circuit: of conti'ol-relay 7 and coinpletestlhe cire/uit of the c'ontro'l relay '10 so as toincrease the voltage ofthesourc-I to a. va-l-ueabove the loadcircuit-voltage when the. device'13 operates to close-its contacts 15and thereby complete a-circuitfor the clo'singcoil 17 of thecircuitbreaker3'.

As shown the eontrol 'device-1-3-is a differential relayof the polarizedtype and coinprises a polarizing-winding-18 connected across a suitablesource of direct current and tliiexdifl'erence between the voltagesof'the source-1 and the load circuit land the eurrent therein flows indirect-iondepending upon-whichvoltage is the higher;- 1

In order: to; effect the closing of the circuit breakQr1-3Arhen vtheswitch-12 is-closed at a time when either, the load circuit -isdeenergized; orthe voltage-thereofi is lower than the miniin uug voltageoftlie. generator,- so. that the, relay- 13 cannot operate efl'ectthe-encrgization of the relay 16, we provide a differential relay 20 whichis responsive to the relative voltage ofiwthesource 1 and the loadcircuit 4. This relay isarra-nged to maintain contacts 21 closed at alltimes except when the voltage of the source 1 exceeds the load circuit 4a predeteru'iined value. Asshown the relay 20 is of the polarized typeand com prises a magnetizing winding connected across a suitable sourceof direct current and a control winding 23 connected across theterminalsof the circuit breaker 3. The relay- 20 together with suitablemeans indicating, that the voltage-of the source 1 is at its minimumvoltage are employed to control the: closing of'the circuit breaker 3.For indicating that the voltage of the source 1 is at itsininiinuii1'\-'alue'we provide the motor operated rheost-at 5 withauxiliary contacts 24: which are arranged in any suitable manner,examples of which are well-known in the art, so that they are closedwhen all of the resistance of therheostatis connected in the circuitoftheshuntfield winding 6. The contacts 21 and 24: are connected in seriesin a circuitfor the closing coil 17 of the circuitbreaker 3 which iscompleted when the con- "trol switch l2 is closed.

24 represents any-suitable control device for-controlling theoperationof the motoropera-tedrheosta't 5 ,ait'er the circuit breaker ils'elosedso as to'niaintaina predetermined generator voltage or currentoutput; In actual' practicethe control device 24 may be an automaticdevice, e1i'amples' of which are well lm'ojvn inthe art, whichiis'responsive to the' ele'et-ricahcondition it is desired tomaintaintThe'operation-"ofthe'arrangement shown is as'foll'ows; "It will be'assumed first; that the source 1 is in operatiom'th'at the load circuit-is energized=by some other source, and that. the control switch 12i'sclosed at a time when the voltage of the source 1 is higher than theload circuit'volt-ageso' that the contacts 15 of the relay 13 are'closecl'and the contacts 21 of relay-20' are open:

The closing of the switch'12coi'npletes a circuit for the control-relay7 from one side of a; suitable 'coIitrol' circuit-' through switch 12,auxiliary-contacts "-25" on the circuit breaker ayeoadaetor'zc, contacts2701? relay 16; conductor 28, coil of relay 7 to the other side ofthecontrol-circuit. Relay 7 by closing its contacts 29 completes a circuitfor the motor '8"so that motor'8 rotates in a dircction to insertresistance into the circuit of" the shuntfield winding 6 and therebydecrease the voltage of the source 1 tea value below theloadcircuitvoltage. The'circuit of the motor- 8 is from one side ofasuitable control circuitthrough limit switch contacts 30 on therheostat- 5' which are closed except when all of the resistance of therheostat-is connected in the shunt field circuit, conluu ductor 31,contacts 29 of relay 7, field winding 9 and the armature of motor 8 tothe other side of the control circuit.

As soon as the voltage of the source 1 has been decreased to a valueslightly below the voltage of the load circuit 1, relay 13 operates toopen its contacts 15 and closes its contacts W I 14 thereby completing acircuit tor the relay 16. This circuit is from one side of the controlcircuit through switch 12, auxiliary contacts 25 on the circuit breaker3, conductor 26,vcontacts.1 1 ofrelay 13, conductor 32, coil of relay1G. to the other side of the control circuit. Relay 1G by closing itscontacts 33 completes alocking circuit for itself which is independentof the contacts lat of relay l3. Relay 16 by opening its contacts 27opens the circuit of relay .7 so to prevent further reductionot' thesource-voltage and by closing its contacts completes a circuit for therelay l to effect an increase inthc voltage of the,source 1.Thecircuitbf the relay is from. one side of.- thc control: circuit.through suit ch12, auxiliary-contacts on the circuit breaker .3,-conductor 26,. contacts 340,1 relay 16, conductor 3,5,coil of relay .10-to the other.

side of the control circuit. Relay.10 byclosing its contacts. 3t}completes acircuit fori the motor.8 sot-hat the motor operates in adirection to cut out resistance from the circuit. of

: the field winding 6., Thiscircuit isfrom one 1 its contacts'15-a-ndthereby completes weir-1 cuit' for the .closingcoiL-17 of thei circuitbreaker 3. This circuit-is from.one; sjide of. the control circuitthrough control switch '12,; auxiliary COlltflCtSQnjrOIl the circuitbreaker 3,;

; conductor 26, contacts 39 ofirelay lfi cons,

duetor 40, contacts 15 ofrelay-13,.eonductpr: 41, closing coil 1-7Htothe otlierside of; the control circuit. Circuit breaker 3 lwclosing; itsauxiliary contacts 42 completes a locking;

,4 1 circuit for its closing coil-1T whichY is inde-- 7 either relay 7or relay 10 asdesire If the control switch 12 isclosed at a time.when'the loadcircuit voltage is less thanthe, voltage of the source llsothat the contactsl; of relay 13 are closed, the relay 16 is energized assoon as the control switch 12 is closed, whereupon the voltage of thesource 1 is immediatelyraised to a value above the load circuit voltagewhen the relay 13 closes its contacts 15 and effects the closing of thecircuit breaker 3 in the manner above described, I

It will now be assumed that the control switch 12 is closed at a; timewhen the load circuit is not energized by, another source and,therefore, the voltage of source 1 is still greater than the loadcircuit voltage after the rheostat 5 hasbeen moved so that all of itsresistance is in the circuit of the shunt field \vinding ti. The closingoi switch 12 eli'ects in the inanneimabove. described. theenergizat-ionpfthe relay 7- which in turn causes the mot0r 8 torotate ina direction to insert resistance into ithe circuit of the field winding(S Afte I-ga predetermined amount of resistance has been inserted in theshunt field. circuit, auxiliary contacts 30 in the circuit ofmotonfiandjts-field winding 9 are opened and auxiliary. contacts 24; areclosed. Ifthe voltage ofthe source does not exceed the load: circuit,voltageby, more than a predetermined amount so thatthe contacts 21 areopen, the closing oi thea uiriliary. contacts 24 completes a circ uitfor the closing:;co'il '17e to effect the closing of;thecircuitbreakenii This circuit is from; Qnes idepf; the control circuit, throughswitch-{1 5 au iliary contacts, 25 on circuit hre gl'i conductor 26,auxiliary contacts 24, onfrheostat..5,l,conductor44, contacts 21 ofrelay 2Q,;conductor t0 c0ntacts15; of relay 13 which: are close dgsince' the-"source voltage is greater than the loadcircuit voltage,con- QQiOIAJPl-filQSi g'zco l l oh th r sid f thefiontitol 1 eixnii" lif1: I: i Z :eWhiI have inacc r g w t p ent statutes showngand {describedour invention as applied to a pai'ticularjsystemand as mbodying Y3 QUSd8Qe di g ammatically indicated,;. changes and modifications will be?obvious to tl oseiskilled in the art and we.- therefore; ai nin theappended claims to cover-5 all; ,-such changes and; modifications {asfall withinthe-{true spiri and-scope of; our in- Zjv What;weclaim;as.new and desire to secure.

b, A Letters- Patent; of the United: States-,- is

load; the source: to, theload- 1 circuit; means. for; ad justing thevoltage otsaid source, means for, controlling the-operation; of :saidivoltage adjusting means/comprising Ea; device responsive tothew-relative volta-ges of said-sourceand said r-load ci-rcuit andarranged-to cause the voltage -adju sting;rneansto increase the voltageof saidsourc'e jwhen-it is lower than the loadcircuit molt-age, Band 3means controlled by saiddevice for-efi'ecting the: closing of saidswitching; means only .after} SiIididQViCQ- has first effected theoperation of said voltage switching means is open-and to effect thecl0sadjusting means to increase the source voltage.

2. In combination, a source of current, a load circuit, switching meansfor connecting the source to the load circuit, means for adjusting thevoltage of said source, a relay for controlling the operation of saidvoltage adj usting means, said relay being arranged when in one positionto eifectthe operation of said voltage adjustingmeans to lower thevoltage of said source and when in another position to effect theoperation of said voltage adjusting means to raise the voltage of saidsource, and means responsive to the relative voltages of the source andload circuit arranged when the voltage of the source is lower than theload circuit voltage to efl'ect the operation of said relay to itsvoltage raising position, and when the voltage of the sourcesubsequently exceeds the voltage of the load circuit, to ellect theclosing of said switchingmeans.

3. In combination, a source of current, a

load circuit switching means for connecting the source to the loadcircuit, Ineans for adjustingthe voltage of saidsource comprising arelayarranged inoneposition t 'o-etf'ect the lowering ot the sourcevoltage-and inanother position to ellect' the raising of the sourcevolt-age, and meansresponsive to the, relative voltages of saidsourceandsaid load circuit-arrangedto move said-relay from-voltage loweringposition to vol-'tageraising- -position when the veltage-of'tlie-sourceis less than-the voltage of'the-loa'cl circuit-, andcontactscontrolledby sa id relative- 'vol tlage responsive means arrangedto cooperate with contacts of sa id relayfor eifegting the closingsaidswitching means when said relayis' n its-voltage raising position andthe voltage of said sourceis'hi'g-her than the voltage of said 'loadcircuit.

4. In combination, a-

below theloa-d circuit voltageto avalueabove theload circuit -voltage.-

5'; -l'n combination, a. source of current, a

load eircuit; switching means-forconnectingthe source'tothe loadcircuit, means'for'adjusting thevoltage of said sourctg me'ansresponsiveto: the relative voltages of-the source and load' circuit forcontrolling the operation offsaid: voltages adjusting means to increaseandwlccrease the source voltage while said source of current, a loadcircuit, switching meansfor' connecting the source'to theload*oireuit-,-means' for ad justing-- the voltage of said" source, andmeans ing of said switching means when the source voltage is increasedfrom a value below the load circuit voltage to a value above the loadcircuit voltage, and means controlled by the voltage of such source foretiecting the closing of said switching means independently of saidrelative voltage responsive means when the voltage of said source hasbeen reduced to a predetermined value.

6. In combination, a source of current, aload circuit, switching meansfor connecting the source to the load circuit, means for adjusting thevoltage of said source, means responsive to the relative voltages of thesource and load circuit for controlling the operation of said voltageadjusting means to increase and decrease the source voltage while saidswitching means is open-and to effect the closing of said switchingmeans when the source voltage is increased from a value below the loadcircuit voltage to. a value above the load circuit voltage, and-othermeans controlled by the voltage ofsaid'source for effecting the closingof said-switchingmeans independently of said relative voltage responsivemeans when the voltage of-said source has been reduced to apredetermined value and the voltage of said source does noteirceedtheloadcircuit voltage more than apredetermined amount.

7. In combination, asource of current, a load circuit, switchingmeansfor connecting the source to the load circuit, means for ad"- justing'the voltage of said source comprising a relay arranged in oneposition toeifect the lowering of the sourcevoltag and in another position toeflect the raising of the source voltage, means responsive to=therelative voltages of said' source' and "said load circuit arrangedtomove'said relayfrom voltage lowering position to voltage raisingposition when the voltage of the source is less than the voltage-of theload circuit, contacts controlled by said relative voltage responsivemeans arranged to cooperate with contacts on said relay fore-losing saidswitching means when said-relay is in volt-age raising position and thevoltage of said source-is higher than thevoltage of said load circuit,other means responsive to the relative voltages of said source and loadcircuit, and contacts controlled-by said last mentioned relative voltageresponsive meansand said voltage adj usting means for-effectingtheclosing of said switching means when the voltage difference betweenthesouree and load circuit isless than apredetermined value and'thevoltage adjusting means-is'in a predetermined condition. v

8. In combination, a source of current, a load circuit, switching meansfor connecting the source tothe load circuit, and meansoperative toeffect the closing of said switching means onlywhcn the volt-age of'saidsource is greater than but does not exceed the voltage of the loadcircuit more than a predetermined amount.

9. In combination, a source of current, a load circuit, switching meansfor connecting the source of the load circuit, means for adjusting thevoltage of said source, and means operative to effect the closing ofsaid circuit breaker only when the voltage adjusting means has reducedthe source voltage to a predetermined minimum value and the voltage ofsaid source does not exceed the load circuit voltage more than apredetermined amount.

10. In combihationfa source of current, a load circuit, switching meansfor connecting the source to the load circuit, means for adjusting thevoltage of said source, a control circuit for said switching means,contacts in said circuit arranged to be closed when said volta eadjusting means occupies a predetermined position, means responsive tothe relative voltages of said source and load circuit, and othercontacts in said control circuit controlled by said voltage responsivemeans so as to be opened only when the source voltage exceeds the loadcircuit voltage a predetermined amount.

11. In combination, it source of current, an electric circuit, switchingmeans for connecting said source to said circuit, means for adjustingthe voltage of said source, control means arranged when deenergized tocause said voltage adjusting means to decrease the voltage of saidsource and when energized to cause said voltage adjusting means toincrease the voltage of said source, and means responsive to therelative voltages of said source and circuit to" energize said controlmeans when the voltage of said source is below the voltage of saidcircuit and to effect the closing of said switching means when thevoltage of said source is higher than the voltage of said circuit andsaid control means is energized.

12. In combination, a source of current, an electric circuit, switchinxmeans for connecting said source to said circuit, means for adjustingthe voltage of said source, a control relay arranged when deenergized tocause said voltage adjusting means to decrease the voltage of saidsource and when energized to cause said voltage adjusting means toincrease the voltage of said source, a differential relay responsive tothe relative voltages of said source and circuit to energize saidcontrol relay when the voltage of said source is below the voltage ofsaid circuit and to effect the connection of said source to said circuitwhen the voltage of said source is higher than the voltage of saidcircuitand said control relay is energized and a relay responsive to therelative voltages of said source and circuit arranged to effect theconnection of said source to said circuit when the voltage of saidsource has been decreased to a predetermined value and the voltagedifference between said source and circuit voltages is less than apredetermined amount.

In witness whereof, we have hereunto respectively set our hands the 18thday of July 1927, and the 20th day of July, 1927.

HERMAN BANY. HAROLD T. SEELEY.

